Predicting IBD Treatment Outcomes With Gut Microbiome Analysis

Inclusion Criteria: CD patients: * Adult patients ≥19 years old and ≤ 80 years old. * CD with distal small bowel and/or colonic involvement that is endoscopically assessable with colonoscopy. * Undergoing colonoscopy as part of routine clinical care. * Active or quiescent disease. * Active disease will be defined as a simple endoscopic score for CD (SES-CD). * Quiescent disease is defined as an SES-CD \<3. * Mild active disease will be defined as a SES-CD of 3-6, or 3 with isolated ileal CD. * Moderate/severe active disease will be defined as a simple endoscopic score for CD (SES-CD) ≥ 7 or ≥ 4 for isolated ileal CD. Non-IBD controls: * Adult patients ≥ 19 years old and ≤ 80 years old. * Undergoing colonoscopy as part of colorectal screening. Exclusion Criteria: CD patients: * Active perianal CD - defined as collection on MRI or clinically active fistula (i.e., draining fistula). * Proximal small bowel (defined as not endoscopically assessable by colonoscopy) or isolated upper GI CD. * Colectomy or Proctocolectomy. * Pouch, J-Pouch or Reversed pouch surgery. * Short Bowel Syndrome (SBS) diagnosis. * Antibiotics in the last 2 months for any indication. * Gastroenteritis or travel outside of Canada and the United States in the last month. * Colorectal cancer, high-grade dysplasia or a polyp ≥2cm diagnosed at baseline endoscopy. * Pregnant or breastfeeding. * Bowel resection within the preceding 4 months. * Primary sclerosing cholangitis. Non-IBD controls: * Found to have inflammation (deemed by endoscopist) at colonoscopy. * History of IBD in 1st degree relative. * Antibiotics in the last 2 months. * Gastroenteritis or travel outside of Canada and the United States in the last month. * Pregnant or breastfeeding. * Previous bowel surgeries.